Seachem Prime Use Advice Please

Lots of people use Prime. It is very concentrated so works out cheaper to use despite the purchase price, and it 'detoxifies' ammonia.

Regarding prime affecting test results, it is only the ammonia one that has the problem as one of the ingredients in Prime interferes with the chemical reaction in the ammonia test used in most home testing kits.
Prime does not interfere with any other test we do.


Once your bottle finally runs out, depending on what your water company uses to disinfect your tapwater, there are other alternatives. I use API Tap Water Conditioner. This is also very concentrated (1 drop per 3.8 litres for chlorine, 3 drops for chloramine) but it does not detoxify ammonia. As I have chlorine in my tapwater it is not a problem for me, but with chloramine you would need to use a separate product to detoxify the ammonia made from the chloramine until the filter bacteria have had time to remove it.

Ignore what I said earlier about Prime interfering with the test - I've just looked on Seachem's website.

Seachem's website says

A Nessler based kit will not read ammonia properly if you are using Prime®... it will look "off scale", sort of a muddy brown (incidentally a Nessler kit will not work with any other products similar to Prime®). A salicylate based kit can be used, but with caution. Under the conditions of a salicylate kit the ammonia-Prime complex will be broken down eventually giving a false reading of ammonia (same as with other products like Prime®), so the key with a salicylate kit is to take the reading right away.

The Nessler test goes yellower the more ammonia there is then brownish; the salicylate test goes green with more ammonia. I know the API ammonia tester is salicylate as that goes green as you go up the colour chart. I think most home testers are salicylate as the Nessler reagent is a mercury compound, not very nice in the home.



I have just been discussing this with my husband. I have a 40 year old degree in chemistry and I've forgotten a lot. Husband has a doctorate in chemistry and he's also forgotten a lot. Younger son has a degree in chemistry and he's currently doing research for a doctorate (admittedly in theoretical chemistry) so he won't have forgotten nearly as much as us. We'll be seeing him over Christmas so I'll pick his brains then.

But in the mean time:
Ammonia dissolves in water; some of it is in the form of ammonia, some in the form ammonium. Ammonium is much less toxic to fish than ammonia. The two are in an equilibrium, and the amount in each form is determined by a combination of temperature and pH. The higher the pH, the more there is in the toxic ammonia form; and the warmer the water, the more ammonia there is. Salicylate testers measure both ammonia and ammonium together. This is why a lot of people say these testers are useless, they don't tell you how much of the total is ammonia.
Prime and other similar products are designed for use with chloramine as the water disinfectant, which is more widely used in the US than the UK. They break the chloramine up into chlorine and ammonia, then detoxify the ammonia part until the filter bacteria can remove it. But the website doesn't say how exactly, just that it forms a Prime-ammonia complex. The data sheet says it contains complexed hydrosulfite salts but these are the chlorine removing chemicals.  They don't say what they use to 'detoxify' ammonia and nitrite.

The best I can make of what they are saying is that something in Prime binds ammonia (thus removing it from harming the fish) leaving the less toxic ammonium in the water. And the test kits are only measuring ammonium not both. Then the complex breaks down liberating the ammonia and the test kit reads both again. But I don't understand how the complexed-ammonia-plus-free-ammonium scenario can be the accurate one with the liberated-ammonia-plus-ammonium being the false one.

Leave this one with me till I can ask my son. He has also worked for a water testing company which may help him shed some light on this.